This invention relates to an adjustable pouch form, fill, seal machine wherein a web is formed into a continuous series of pouches separated by transverse seals. More particularly, the invention relates to apparatus for locating the position of each seal on the web and employing that information to cut the web on the center of each seal to form individual pouches.
The apparatus of the present invention is an improvement in the apparatus of U. S. Pat. No. 4,956,964 whose disclosure is incorporated herein by reference.
In the apparatus described in the '964 patent, a web of heat-sealable film or a laminate containing a ply of heat-sealable film is longitudinally folded upon itself and thereafter transversely heat-sealed to form individual pouches interconnected at their seals. The web may have no printing or may have random printing without registration marks. Where a web has registration marks through which it is possible to locate the seals so that a cutting knife can cut on the center of the seals, it is easy enough to use an electric eye to locate the registration mark and effect cutting using the information obtained by the electric eye.
The '964 patent addresses the problem of locating the seal where there are no registration marks present. The patent discloses apparatus that includes a walking star, that is, a rotary element having uniformly spaced arms that project into individual pouches as the pouches pass the walking star. The walking star is rotated by the engagement of the edge of each arm by the seal that defines the pouch. Thus, the annular position of the walking star is directly related to the longitudinal position of the seal on the web. An encoding system transmits the information concerning the annular position of the walking star to a computer which in turn operates the cutting apparatus.
A problem has arisen that in some circumstances the walking star becomes disengaged from the pouches causing a loss of registration. The operator might have to stop the machine to tuck the arms of the star back into the pouches.